Low-Loss GaAs-AlxGa1-xAs Double Heterostructure Directional Coupler

Abstract

The interest of III-V semiconductors for optical monolithic integration is well established. A fundamental problem to solve before being able to take full advantage of the large potentiality of semiconductor monolithic circuits is to realize single-mode waveguides in these materials exhibiting very low propagation loss (≲ 1 dB/cm). For instance, the problem affects electro-optic directional couplers, which are considered as basic unit in integrated optics. In spite of obvious qualities (especially concerning expected electrical bandwidth), the relatively large optical loss exhibited by the most efficient ones has precluded their use in systems. We report here the realization of an electro-optic directional coupler using double-heterostructure GaAs-AlxGa1-xAs waveguides, which provides lower propagation loss (1dB/cm) compared to previously reported results, while maintaining good switching properties (< 15 V) both at 1.3 and 1.5μm.